Received: 25 September 2018 | Revised: 25 September 2019 | Accepted: 14 October 2019 DOI: 10.1002/fes3.190

ORIGINAL RESEARCH

On‐farm seed priming and fertilizer micro‐dosing: Agronomic and economic responses of maize in semi‐arid Ethiopia

Getachew Sime1,2 | Jens B. Aune2

1Department of Biology, College of Natural Sciences, Hawassa University, Hawassa, Abstract Ethiopia On‐farm seed priming has been reported to improve emergence, crop establishment, 2Department of International and yield besides improving economic benefits in dryland agriculture. These ben- Environment and Development Studies efits can further be improved by fertilizer micro‐dosing. The purpose of this study (Noragric), Norwegian University of Life Sciences (NMBU), Ås, Norway was to investigate the effect of on‐farm seed priming and fertilizer micro‐dosing on the agronomic and economic returns of maize (Zea mays L. var. Melkassa‐2) in Correspondence semi‐arid agro‐ecological conditions in Ethiopia. The experiments consisted of four Getachew Sime, Department of Biology, College of Natural Sciences, Hawassa treatments: no priming and no fertilizer; no priming and fertilizer; priming and no University, Hawassa, Ethiopia. fertilizer; and priming and fertilizer. The experiments were conducted in three loca- Emails: [email protected]; getachew. [email protected] tions viz., Melkassa, Ziway, and Hawassa in the central Rift Valley. Analysis of vari- ance for each location was performed separately at p ˂ .05. Results of each location Funding information were similar over the experimentation years, and hence, there was no need for carry- Norwegian Ministry of Foreign Affairs ing out combined analysis. Regardless of fertilization, primed plants showed faster emergence; better uniform crop stands; more vigorous plants; earlier flowering; ear- lier harvest; and higher grain and stover yield than no primed plants. Germination was 2–3 days earlier, and flowering and maturation of primed plants were 10 to 13 days earlier than no primed plants. Average grain yield increased by 11, 8, and 6% in Melkassa, Ziway, and Hawassa, respectively, by priming over no priming. Fertilizer micro‐dosing combined with priming further improved most of the agro- nomic characters. Fertilizer micro‐dosing combined with priming increased the aver- age grain yield by 75, 69, and 33% in Melkassa, Ziway, and Hawassa, respectively. The economic returns also increased in the same pattern as the agronomic responses for priming, micro‐dosing or their combination. To realize the potential of seed prim- ing of increasing agronomic performances, future research and development efforts should focus on understanding the possible underling physiological and biochemical basis of this poorly understood process with the different priming techniques.

KEYWORDS agro‐economic return, dryland agriculture, fertilizer micro‐dosing, rainfall variability, seed priming

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2019 The Authors. Food and Energy Security published by John Wiley & Sons Ltd. and the Association of Applied Biologists.

wileyonlinelibrary.com/journal/fes3 | 1 of 13  Food Energy Secur. 2019;00:e190. https://doi.org/10.1002/fes3.190 2 of 13 | SIME and AUNE 1 | INTRODUCTION There are several priming methods, which have been em- ployed so far. The most commonly used methods are osmo‐ Maize (Zea mays L.) is a cereal crop that is grown widely priming, soaking in a solution of osmoticum (Mahboob et throughout the world in a range of agro‐ecological environ- al., 2015; Rouhi et al., 2011), halo‐priming, soaking in salt ments and is important both to subsistence and commercial solution (Nawaz, Amjad, Pervez, & Afzal, 2011; Tian et farmers (FAO, 2004). In Ethiopia, maize is cultivated in al., 2014), solid matrix priming, priming using solid carri- all major agro‐ecological zones, between elevations of 500 ers (Khan, 1992; Olszewski, Goldsmith, Guthrie, & Young, and 2,600 meters above sea level (Mulatu, Bogale, Tolessa, 2012), and hydro‐priming, soaking in water (Afzal et al., Desalegne, & Afeta, 1992). It plays a central role in food 2002; Ahammad, Rahman, & Ali, 2014; Harris et al., 1999). security, especially in the rural areas of Ethiopia. Per cap- This study used hydro‐priming, which is the most cost ef- ita consumption of maize in rural areas is estimated at about fective and practical method that needs only water to prime 45 kg/year. More than 80% is consumed at the household seeds. Hydro‐priming is a low cost, low risk, and simple level, with commercial marketing largely limited to large‐ practice that can be used by farmers to improve their liveli- scale producers. Although there are large‐scale commer- hood. It involves soaking seed in water (usually overnight), cial farms engaging in maize production, smallholders and surface‐drying, and then sowing the same day. Yet, soaked subsistence farmers represent 95% of its production (FAO, seeds can be managed as nonprimed seeds if they are sur- 2014). Moreover, among the cereals produced by farmers in face‐dried and kept dry, and can be kept for several days and Ethiopia, maize has the largest smallholder coverage with 8 used for sowing. Moreover, farmers can prime their own seed million farmers compared to 5.8 million for teff (Eragrostis once they know the “safe limits” that helps to avoid seed or tef (Zucc.) Trotter) and 4.2 million for wheat. It is a staple and seedling damage (Harris et al., 2001; Murungu et al., 2004). critical crop to smallholder livelihoods, especially to semi‐ Moreover, the consequence of drying seeds after priming is arid farming communities where it is cultivated by over 95% opportunities for farmers to “add value” to their seeds, which of smallholders. Maize is the crop that produces calories at delivers nutrient supplements and increase resistance to pests the lowest cost, providing 1.5 times and twice the calories and diseases (Harris, 2006). per dollar compared to wheat and teff, respectively (CSA, The aim of seed priming is, therefore, to rapidly hydrate 2013). Therefore, increasing the productivity of maize could seed in order to shorten the time to emerge. It advances ger- promote Ethiopia's food production and reduce the national mination by inducing a wide range of biochemical changes food deficit. in seed. It is, thus, associated with faster seed germination, The semi‐arid Africa is dominated by low yield and higher seedling vigor, stand uniformity, earlier flowering rain‐fed farming system. The farming system is charac- and maturation, higher yield, lower risk, and allows farmers terized by slow seed emergence, low vigor of seedlings, a much wider choice of farm management options (Harris, patchy plant stands, and frequent crop failure or yield re- 2006; Harris et al., 1999, 2001; Rashid, Harris, Hollington, duction (Camara, Camara, Berthe, & Oswald, 2013; Harris & Khattak, 2002). Seed prioming has been shown to improve et al., 2001; Sime & Aune, 2019; Sori & Tomer, 2011). germination and establishment, promote earlier flowering, These are common challenges in maize production in the and greater yield in the semi‐arid tropics (Finch‐Savage, Dent, semi‐arid Rift Valley region of Ethiopia (Kassie et al., & Clark, 2004; Harris et al., 1999, 2001; Osman, Abdalla, 2014; Sime & Aune, 2019). The region's maize production Mekki, Elhag, & Aune, 2010). In particular, the benefits is highly variable due to occurrence of frequent dry spells, later in the growth of maize were much greater than might be soil moisture stress, poor soil fertility, and lack of access to expected from emergence 1–3 days earlier (Murungu et al., appropriate maize varieties. Consequently, the agronomic 2004). Although the level varies, priming has been used to and economic benefits from maize are apparently low and increase productivity of maize in Zimbabwe, India, Pakistan, are largely responsible for the low food security in the re- and Bangladesh (Harris et al., 1999, 2001; Murungu et al., gion (Beshir & Wegary, 2014; Biazin & Stroosnijder, 2012; 2004). Kassie et al., 2014). Improvement in water use efficiency In association with seed priming, the other technology for enhanced drought tolerance and improved crop yield that can increase the productivity of maize in the semi‐trop- can be achieved by different agronomic practices like on‐ ics is fertilizer micro‐dosing (Abdalla et al., 2015; Camara farm seed priming (Harris, Joshi, Khan, Gothkar, & Sodhi, et al., 2013; Sime & Aune, 2016). There are few reports on 1999; Harris et al., 2001). In soil moisture stressed condi- the combined effect of seed priming and fertilizer micro‐dos- tions, it is possible that primed seedlings experience less ing on crop production. The key results of these studies, that stress due to faster germination and growth (Murungu et is, increased yield in sorghum and pearl millet in western al., 2004). Thus, seed priming can be used as a strategy to Sudan (Aune & Ousman, 2011), maize in semi‐arid Ethiopia mitigate the impacts of climatic variability and soil mois- (Sime & Aune, 2016), and sorghum and millet in the Sahel ture stress on maize production. (Aune & Bationo, 2008). These studies were conducted SIME and AUNE | 3 of 13 under conventional tillage (Aune & Bationo, 2008; Aune & increases yields and economic profitability (Camara et al., Ousman, 2011) and minimum tillage (Sime & Aune, 2016). 2013). Such a method of fertilizer application entails a Author's previous work (Sime & Aune, 2016), neverthe- minimal economic risk and can contribute to higher yields less, did not evaluate the separate effect of seed priming and and improve food security and farmers’ income (Aune & fertilizer micro‐dosing in maize, despite that the study was Ousman, 2011; Camara et al., 2013; Sime & Aune, 2014). conducted under minimum tillage system. Further, Sime and For traditional agriculture with low yields and no fertilizer Aune (2014) evaluated only the separate effect of fertilizer input, micro‐dosing could be used as an entry point toward a micro‐dosing in maize, under conventional tillage system. more productive and fertilizer input‐based agriculture (Aune Hence, the present study evaluates, as a new aspect, both & Bationo, 2008; Camara et al., 2013). Moreover, to ensure separate and combined effects of seed priming and fertilizer agronomic sustainability and mitigate nutrient depletion, the micro‐dosing on the agronomic and economic responses in use of organic manure or compost together with inorganic maize, under the conventional tillage system. fertilizer in micro‐dosing is promoted in the SSA (Camara et We hypothesized that on‐farm seed priming, fertilizer al., 2013). micro‐dosing or their combination increases the agro‐eco- Because the micro‐dosing technology is low cost, low nomic benefits in maize production. Each of the technologies risk, and gives immediate agronomic and economic benefits, can individually increase maize productivity. However, com- it may be attractive to farmers (Aune, Doumbia, & Berthe, bining themcan further improve the agronomic performance 2007; Aune, Traoré, & Mamadou, 2012; Sime & Aune, 2014). and economic returns, thus, providing a potentially viable op- Such immediate benefits are decisive in technology adoption. tion for resource‐poor farmers. The objective of this paper is, It is only when farmers can generate positive returns from the therefore, to evaluate the individual and combined effects of alternative practice that they adopt it. Micro‐dosing of fer- on‐farm priming, fertilizer micro‐dosing on maize agronomic tilizers has shown consistent results in on‐station and large‐ performances and the economic returns, in the semi‐arid cen- scale on‐farm studies. It appears to be a promising option for tral Rift Valley of Ethiopia. increasing crop productivity with a relatively limited input of resources (Camara et al., 2013). Moreover, smallholder farm- ers need robust technologies, which are not too demanding on 2 | POTENTIAL OF SEED skills, knowledge, and resources, but which improve produc- PRIMING, FERTILIZER tivity and/or yield stability. In addition to improving yields MICRO‐DOSING, AND THEIR and minimizing input costs, fertilizer micro‐dosing enhances COMBINATION IN AFRICAN fertilizer use efficiency, increases nutrient uptake, and saves AGRICULTURE fertilizer. For instance, it was reported to increase yield from 44% to 120% and farm income from 52% to 134% compared Efficient soil fertility management that aims at maximiz- to the recommended dosage and farmers’ practice in Niger ing the agronomic efficiency of applied nutrients is vital for (Tabo, Bationo, Diallo, Hassane, & Koala, 2006). In addi- intensifying agriculture in Africa (Vanlauwe et al., 2011). tion, micro‐dosing can be applied after sowing without much Importantly, the use of proper fertilizer management and the penalty on yield (Camara et al., 2013; Hayashi, Abdoulaye, adaptation of input application rates following soil fertility Gerard, & Bationo, 2008). The delayed fertilizer application gradients are important (Vanlauwe et al., 2011). Addressing can lessen the financial burden of farmers during the sowing soil fertility decline is key to overcoming hunger in Africa period and give them another option to increase productivity (Sanchez, 2002). Nitrogen and phosphorus are often the most and economic returns. Farmers can then have greater flexibil- limiting nutrients for crop production in the tropics (Osmond ity in managing their labor and cash resources. & Riha, 1996). As a result, to reverse the trend of declin- Other technologies that are compatible with micro‐dos- ing per capita food production, more intensive land use with ing are seed priming (Aune & Ousman, 2011; Camara et fertilizer application has become necessary. Such a method al., 2013), ridging for water conservation (Aune & Ousman, can attract the poorest farmers’ interest in fertilizer applica- 2011; Camara et al., 2013), organic fertilizers (Camara tion. Fertilizer micro‐dosing is an efficient fertilizer applica- et al., 2013), and surface mulching (Sime & Aune, 2016). tion method that can significantly reduce fertilizer rates and In marginally arid, semi‐arid, and rain‐fed areas in Africa, risks, and increases yields, thus, can be an available option low‐vigor seedlings and patchy plant stands resulting from for fertilizer application in Africa. Seed priming alone or in failure of the crop to emerge quickly and uniformly are com- combination with fertilizer micro‐dosing could have similar mon challenges for farmers (Camara et al., 2013; Harris et potentials for intensifying agricultural productivity in Africa. al., 2001; Sime & Aune, 2016; Sori & Tomer, 2011). When Micro‐dosing technology was developed to maximize the farmers face patchy seedling establishment, they may re‐sow, return on fertilizer investment (ICRISAT, 2009). Findings although this entails increased labor and financial costs. Seed from a previous study indicated that micro‐dosing technology priming advances germination by inducing a wide range of 4 of 13 | SIME and AUNE

FIGURE 1 Location map of the study sites biochemical changes in the seed. It is associated with faster of seed priming and micro‐dosing or their combination is seed germination, higher seedling vigor, improved stand uni- lacking and requires further investigation in Africa. formity, earlier flowering, maturation and harvesting, and higher yields (Ahammad et al., 2014; Aune et al., 2012). For instance, in the low‐rainfall Africa, it increased yield 3 | MATERIALS AND METHODS in maize in Zimbabwe (Harris et al., 2001), in sorghum and millet in Sudan (Aune & Ousman, 2011), and in pearl millet 3.1 | Description of experimental sites in Mali (Aune et al., 2012). Additionally, the combination The study was carried out at three sites in the central Rift of seed priming with micro‐dosing improves agronomic and Valley, namely Ziway, Melkassa, and Hawassa (Figure economic returns in millet in low‐rainfall regions in Mali 1). Ziway and Melkassa are located in East Shoa Zone in (Aune et al., 2012), in sorghum and millet in west Africa, Oromia Regional State while Hawassa lies in Sidama Zone in sorghum and millet in Sudan (Aune & Ousman, 2011), in in Southern Nations, Nationalities and People Regional State, sorghum, groundnut, sesame, and cowpea in Sudan (Abdalla in southern Ethiopia. Melkassa and Ziway are located in the et al., 2015), and in maize in Ethiopia (Sime & Aune, 2016). semi‐arid agro‐ecological zones. Hawassa is in the moist Such a combination also decreases the risk of investing in mid‐highlands. fertilizer, keeping the value cost ratio above the minimum re- quirement (Aune et al., 2012; Sime & Aune, 2016). During low‐rainfall, semi‐arid, and rain‐fed Africa, seed priming is, 3.2 | Melkassa therefore, an important option available to farmers. Although Melkassa is located at 8°4′N latitude, 39°31′E longitude and seed priming and fertilizer micro‐dosing are important alter- lies at an altitude 1,550 m above sea level (m.a.s.l.). It is lo- natives for farmers in low‐rainfall, semi‐arid, and rain‐fed cated at 115 km southeastern of Addis Ababa. Melkassa re- Africa, only few attempts have been made so far to promote ceives a mono‐modal type of rainfall from June to October, their adoption. Empirical reports on adoption rate by farmers which is the main cropping season for early maturing cereals SIME and AUNE | 5 of 13 and pulses (Table 1). The average maximum and minimum Moisture deficit areas occupy more than 60% of the land air temperature during the experimental period was 29°C and mass in Ethiopia (Mersha, 2000). Agriculture in the semi‐arid 14°C, respectively (Sime & Aune, 2014). central Rift Valley is primarily rain‐fed and low yielding. It is affected by physical constraints like low soil fertility, high soil moisture stress, frequent intra‐seasonal dry spells, and 3.3 | Ziway terminal drought (Belay, Bekele, & Ewunetu, 2013; Biazin & Ziway is located at 7°9′N latitude, 38°43′E longitude, an Sterk, 2013; Getachew & Tesfaye, 2015). Climate trends in altitude of 1642 m.a.s.l and 122 km south of Addis Ababa. the region, especially in terms of rainfall and its variability, Ziway receives a bimodal rainfall from April to May and pose major risks to the rain‐fed agriculture. Therefore, the from June to October. June to October is the main cropping region needs specific adaptation strategies to cope with the season for early maturing cereals and pulses (Table 1). Risk‐ risks, sustain farming, and improve food security (Kassie et taking farmers also plant mid‐maturing maize varieties in al., 2014). April, which are often affected by the cessation of rain in late May. The average maximum and minimum air temperature during the experimental period was 28°C and 13°C, respec- 3.5 | Soil physical and chemical properties tively (Sime & Aune, 2014). The soil texture at Ziway is clay loam (40% sand, 32% silt, and 28% clay), with moderately alkaline pH at 8.40, 3.21% or- ganic carbon (OC), 0.25% total nitrogen (TN), and 18.20 mg/ 3.4 | Hawassa kg available P. The soil at Melkassa is loam soil (37% sand, Hawassa is located at 704'N latitude, 38031'E longitude, and 40% silt, and 23% clay), with a slightly alkaline pH at 7.42, lies at an altitude of 1675 m.a.s.l. It is located at 275 km south 1.7% OC, 0.14% TN, and 19.20 mg/kg available P. The soils of Addis Ababa. It receives a bimodal rainfall with peak at Ziway have lower available P and bulk density than the rainfall months in April and July, with the former (March to soils at Melkassa. There are slightly better conditions in the June) being the main cropping season for planting late and chemical properties, including electrical conductivity, OC, mid‐maturing maize varieties (Table 1). The latter (June to TN, exchangeable cations including potassium, sodium, October) is used for growing early maturing crops such as calcium, and magnesium, and cation exchange capacity in maize and pulses. The average maximum and minimum air Ziway soils than in Melkassa soils. Total porosity is similar temperature during the experimental period was 26.5°C and in both sites (Sime & Aune, 2014). 14.0°C, respectively (Sime & Aune, 2014). The soil at Hawassa is a well‐drained loam (46% sand, All the study sites are characterized by a mixed farming 28% silt, and 26% clay), with a slightly acidic pH at 7.1, 2.3% system, where both livestock and crop production are im- OC, 0.19% TN, and 46.40 mg/kg available P. Compared to portant agricultural practices and the mainstay of farmers’ the other two sites, Hawassa is a high potential area for crop livelihoods. Despite providing dung for domestic fuel, cattle production with better soil quality, rainfall, length of grow- are important in the agricultural production system as they ing season, and other agro‐ecological conditions. Because of provide draught and threshing power as well as manure to im- relatively smaller landholding per households, farmers’ soil prove soil fertility. Crop residues are used as livestock feed, management practices are better at Hawassa. Farmers use domestic fuel, and construction material. Mono‐cropping of both organic and inorganic fertilizers. Among others, these cereals is commonly practiced, which is mainly composed of might be the reasons for the remarkably high available P at maize at Ziway and Hawassa, and Teff and maize at Melkassa. Hawassa (Sime & Aune, 2014).

3.6 Treatments, experimental designs, Average total annual and study period rainfall (mm) | TABLE 1 measurements, and analyses Annual Amount of rainfall dur- The treatments were as follows: (January to ing study period (June to December) October) (i) No priming seeds and no fertilizer (P0M0), Annual (ii) No priming and fertilizer (P0Mf), rainfall (iii) Priming and no fertilizer (PM0), and Site 2012 2013 2012 2013 (%) (iv) Priming and fertilizer (PMf). Ziway 598 856 442 732 81 Melkassa 923 924 685 822 82 Where 0 denotes absence of priming or fertilizer application, P Hawassa 948 1,125 876 994 90 denotes priming, M denotes micro‐dosing, and f denotes fertil- Source: Adami Tullu (Ziway) and Melkassa Meteorological Stations. izer application. 6 of 13 | SIME and AUNE The fertilizer rate was 1 g per hill of diammonium and adjusted at 12.5% moisture level. To avoid border effects, phoshate (21%N and 46%P) applied at sowing and 1 g data of all the parameters considered were taken from the four per hill of urea (46%N) applied at maize knee height. The central rows; thus, the net plot size was 9 m2. control did not receive fertilizers. The DAP fertilizer was The agronomic efficiency, risk, and profitability of using applied at planting. Any difference in the effects of the fertilizers were assessed by calculating fertilizer use effi- two types of fertilizer was not considered in the present ciency (FUE), value cost ratio (VCR), and gross margin study. This effect has been already reported in the author's (GM). previous publication (Sime & Aune, 2016). Agronomic and economic responses increased when urea was added, and responses were lower when only DAP fertilizer was 3.6.1 | Agronomic fertilizer use efficiency used. Since emergence was better in primed plants than no FUE: The agronomic FUE of each treatment was computed primed plants, different total amounts of fertilizer were ap- as the difference in yield (kg/ha) between each treatment and plied per ha. This was taken into account in the calculations control divided by the amount of fertilizer applied (kg/ha). of fertilizer use efficiency and economic returns. The treat- Yt−Ct ments were arranged in a randomized complete block de- FUE = Ft sign with four replications. Plot size was 3 by 4.5 m, which corresponds to 6 rows of maize, spaced at 0.75 m between where FUE is the agronomic fertilizer use efficiency of treat- rows, and 0.25 m within rows. The plant population was ment t; Yt is the grain yield of treatment t; Ct the grain yield about 53,333 per ha. Blocks were separated by 1.5 m apart. of the control treatment; and Ft is the rate of fertilizer used Different plots were used for the same treatments each year. for treatment t. One seed was sown per hill at 5 to 7 cm depth. Seedbeds Partial budgeting technique: It was used for the analysis were prepared by oxen with four strips using a traditional of economic efficiency or profitability of each treatment. The plow. Plots were kept weed‐free by hand—weeding and GM was calculated to evaluate the economic response of each hoeing. Weeding was carried out on the third and fifth treatment. Cost of production for each treatment, including week after sowing. The experimental crop was maize vari- fertilizer, seeds, and labor (for priming, planting, fertilizer ety (Zea mays L. var. Melkassa‐2), which has been recom- application, weeding, and harvesting), and revenue generated mended for semi‐arid areas in the central Rift Valley that from the price index for grain yield (averaged over 2012 and matures in about 120–130 days after sowing. It is among 2013 cropping seasons) were collected from local markets early maturing maize varieties released for dryland agri- where farmers buy inputs and sell their produce. Monetary culture in Ethiopia. values related to costs were converted from Ethiopian Birr Before each sowing date, seeds were primed by soaking to US$ at the exchange rate of one US$ equivalent to 18.46 in water overnight for 12 hr, then surface‐dried for 1 hr by Ethiopian Birr. blotting with a dry cloth under shade. Maize seeds can be VCR: Fertilizer profitability is a function of fertilizer re- primed without damage for up to 24 hr (Harris et al., 1999), sponse (kilogram of additional output per kilogram of fer- and farmers tended to prefer at 12 hr soaking time length tilizer used), fertilizer prices, and output prices. For each overnight (Chivasa, Harris, Chiduza, Mashingaidze, & treatment, the VCR was calculated using yield increase of Nyamudeza, 2000; Harris et al., 1999). the treatment compared with the control, price per kg grain, Data were collected for number of days to emerge and to 50% kg fertilizer used and price per kg fertilizer used as follows: germination, seedling uniformity and vigor, duration to 75% Δ ∗ physiological maturity, stover yield, and grain yield. Seedling VCR = Y P uniformity (rated 1 to 5 where: 1 = poor, 2 = low, 3 = moder- Cf ate, 4 = uniform, 5 = very uniform). Seedling vigor (rated 1 to 5 where: 1 = poor, 2 = low, 3 = moderate, 4 = vigorous, 5 = very where ΔY denotes incremental yield gains resulting from fer- vigorous). The scale used for rating seedling uniform and vigor tilizer use between a treatment and control, P denotes price was based on the relative performances of treatments. These per kg of maize, and Cf denotes the cost of dose of fertilizer traits were measured after the seedling was established well, used per hectare. after the second weeding. Days to physiological maturity was This analysis was based on the average yields of each taken when 75% of maize plants in a plot showed dried leaves treatment; where a partial budget was used to calculate the and black scar on the kernels. Stover weight was taken after net profit; VCR was calculated for each treatment. The VCR sun drying for nine to twelve days and when no change was for each treatment measures the increase in revenue relative observed between consecutive measurements. Threshing was to the increased costs compared to the control treatment. It done manually. Grain yield weight at harvest was measured measures the economic (net return) return of fertilizer use. SIME and AUNE | 7 of 13 MAT (days) MAT (days) 132a 125b 122c 115d 0.94 132a 124b 123c 115d 0.99 0.99 0.99 0.52 0.49 , Priming and f VIG (scale) VIG (scale) 2.25c 3.25b 3.00b 4.25a 0.67 2.00c 3.25b 3.50ab 4.00a 0.83 0.59 0.78 11.98 13.58 , No priming and fertilizer micro‐dosing; f M 0 UNI (scale) UNI (scale) 2.00c 3.00b 3.50b 4.50a 0.63 2.00b 3.50a 3.25a 4.25a 0.62 1.13 0.86 22.65 12.56 , Priming and no fertilizer micro‐dosing; PM 0 Hawassa Hawassa PSG (%) PSG (%) 90.25b 90.25b 94.75a 94.75a 0.77 91.5b 91.25b 94.75a 94.5a 0.66 2.06 0.96 1.44 0.54 MAT (days) MAT (days) 128a 124b 117c 112d 1.56 127a 124b 117c 113d 0.99 0.83 0.98 0.45 0.84 , No priming and no fertilizer micro‐dosing; P 0 M 0 VIG (scale) VIG (scale) 2.25c 3.5b 3b 5a 0.59 2.75c 3.75b 3.25ab 4.25a 0.63 0.77 0.90 14.29 11.11 , No priming and fertilizer micro‐dosing; PM f M 0 UNI (scale) UNI (scale) 2.5c 3.5b 3.75ab 4.5a 0.86 2.5c 3.75ab 3.5b 4.5a 0.69 0.86 0.69 15.69 15.69 Ziway Ziway PSG (%) PSG (%) 85.5b 89.5b 93.75a 93.75a 0.82 89.5b 89.25b 94.5a 94.5a 0.97 0.86 0.95 0.61 0.59 MAT (days) MAT (days) 130a 123b 117c 113d 1.29 128a 123b 118c 113d 0.99 1.22 0.98 0.66 0.69 , No priming and no fertilizer micro‐dosing; P 0 M 0 , Priming and fertilizer micro‐dosing; CV (%), Coefficient of Variation LSD, Least Significant Difference. f VIG (scale) VIG (scale) 2.25c 3.25b 3.00b 4.00a 0.54 2.25c 3.25b 3.75ab 4.5a 0.76 0.80 0.81 15.14 11.3 UNI (scale) UNI (scale) 2.25b 3.00b 3.75a 4.25a 0.67 2.00c 3.25b 3.25b 4.25a 0.81 0.67 0.80 13.58 13.1 PSG (%) PSG (%) Melkassa 89.25b 89b 93.75a 93.75a 1.11 Melkassa 88.5b 88.5b 94.25a 94a 0.95 1.16 0.93 0.82 0.79 Effect of priming, micro‐dosing, and combination on maize (var. Melkassa‐2) yield components in 2012 cropping season three sites Effect of priming and fertilizer micro‐dosing on percent germination, seedling uniformity vigor, days to maturity ma ize (var. Melkassa‐2) grown at three locations during the 0.05 0.05 0 f 0 f 0 f 0 f , Priming and no fertilizer micro‐dosing; PM M M M M 0 2 0 0 0 0 Treatment Treatment P P P PM PM R2 P PM PM R CV (%) CV (%) LSD LSD fertilizer micro‐dosing; CV (%), Coefficient of Variation and LSD, Least Significant Difference. PM 2013 cropping season Note: Means in the same column with letter are not significantly different at p value < .05. Abbreviations: PSG, Percent seed germination; UNI, Seedling uniformity (rated 1 to 5 where: 1, poor, 2, low, 3, moderate , 4, uniform, 5, very uniform); VIG, vigor moderate, vigorous, 5, very vigorous); MAT, Physiological maturity; P Note: Means in the same column with letter are not significantly different at p value < .05. Abbreviations: PSG, Percent seed germination; UNI, Seedling uniformity; VIG, vigor; MAT, Physiological maturity; P TABLE 2 TABLE 3 8 of 13 | SIME and AUNE TABLE 4 Effect of priming, micro‐dosing, and combination on maize (var. Melkassa‐2) grain yield (GY) and stover yield (SY) in 2012 and 2013 cropping seasons

Melkassa (kg/ha) Ziway (kg/ha) Hawassa (kg/ha)

2012 2013 2012 2013 2012 2013

Treatment GY SY GY SY GY SY GY SY GY SY GY SY

P0M0 3559d 5889d 3710d 6583d 3867d 6639d 4068d 6889d 6313d 7194d 6640d 7139d

P0Mf 5162b 7444b 6061b 8278b 6137b 8445b 6259b 8778b 7171b 9083c 7527c 8917b

PM0 3799c 6612c 4291c 7083c 4233c 7194c 4338c 7556c 6812c 7750b 6910b 7917c

PMf 6107a 8667a 6633a 9083a 6667a 9111a 6778a 9361a 8472a 9500a 8726a 9945a R2 0.98 0.88 0.99 0.95 0.99 0.94 0.99 0.97 0.96 0.97 0.96 0.99 CV (%) 3.07 6.26 1.35 3.18 1.63 3.51 2.09 2.32 2.94 2.14 2.10 1.74

LSD0.05 220.3 490.1 106.2 380.4 131.4 423.9 173.2 291.3 328.6 276.3 239.4 227.6

Note: Means in the same column with same letter are not significantly different at p value < .05.

Abbreviations: GY, Grain yield; SY, Stover yield; P0M0, No priming and no fertilizer micro‐dosing; P0Mf, No priming and fertilizer micro‐dosing; PM0, Priming and no fertilizer micro‐dosing; and PMf, Priming and fertilizer micro‐dosing; CV (%), Coefficient of Variation and LSD, Least Significant Difference.

TABLE 5 Priming and micro‐dosing effects on fertilizer use statistical analysis of data for each location and season was efficiency and value cost ratio carried separately. The statistical analysis compared the ef- fects of treatment (comparison between treatments) sepa- Hawassa Ziway Melkassa rately on a yearly basis. All the treatments were compared Treatment FUE VCR FUE VCR FUE VCR with each other and the control to assess performances and all

P0M0 – – – – – – the available options for farmers. The results obtained from both seasons across sites were nearly similar, suggesting P0Mf 12 4 24 8 20 6 similar results for the combined analysis. That is why author PMf 25 8 33 10 30 10 did not perform a combined analysis of variance/pooled data PM0 – – – – – – analysis. Further, due to high intra‐and interseasonal rainfall P M 9 3 17 5 14 4 0 f variability in the study areas, authors were also interested in PMf 22 7 25 8 24 8 evaluating the performances of the treatments under different Note: P0Mf and PMf are listed twice in the treatment column with different val- amount of rainfall events. ues because they are compared with different control groups (P0M0 and PM0), under priming and no priming circumstances.

Abbreviations: FUE, Fertilizer use efficiency; VCR, Value cost ratio¸ P0M0, No priming and no fertilizer micro‐dosing; P0Mf, No priming and fertilizer 4 | RESULTS micro‐dosing; PM0, Priming and no fertilization, and PMf, Priming and fertilizer micro‐dosing. Tables 2, 3, and 4 depict the agronomic results of the 2012 and 2013 cropping seasons and Tables 5 and 6 the combined economic results over the two seasons and sites. The agro- Gross Income (GI): It was calculated from grain local nomic results considered in this study were days to emerge, market price. percent seed germination, uniformity, days to maturity and Total Variable Cost (TVC): It was calculated as the sum of yields, while the economic results were fertilizer use ef- labor and input costs. ficiency, value cost ratio, labor, gross income, and gross GM: For each treatment, GM was calculated as the differ- margin. ence between GI and TVC, that is, GM = GI – TVC. 4.1 | Yield components and yields 3.7 | Statistical analyses Individually, both priming and fertilizer micro‐dosing were Analyses of variance were carried out using a statistical able to significantly improve most of the agronomic charac- analysis system (SAS) software version 9.4 (SAS, 2011). ters across sites. Apart from that, generally the highest agro- Wherever there were significant differences, mean separa- nomic returns were obtained at all sites when both priming tions were carried out using the Least Significant Difference and micro‐dosing were combined, particularly seedling uni- (LSD). Significant differences between means of treatments formity, seedling vigor, days to maturity and stover and grain were determined at the 5% significance level (p < .05). The yields (Tables 2, 3, and 4). SIME and AUNE | 9 of 13 TABLE 6 Priming, micro‐dosing, and combination effects on labor requirement (day/ha), gross income, and gross margin (US$ /ha)

Hawassa Ziway Melkassa

Treatment LR GI GM LR GI GM LR GI GM

P0M0 28b 1323d 1245d 28b 911d 808d 28b 840d 715d

PM0 29b 1393c 1312c 29b 950c 844c 29b 890c 788c

P0Mf 42a 1596b 1383b 43a 1397b 1139b 42a 1388b 1020b

PMf 43a 1920a 1704a 44a 1496a 1288a 43a 1427a 1213a LSD (<0.05) 1.5 34.9 35.3 1.6 21 20.5 1.8 23.5 23.4

Note: Means in the same column with same letter are not significantly different at p value < .05.

Abbreviations: LR, Labor; GI, Gross Income; GM, Gross Margin; P0M0, No priming and no fertilization; P0Mf, No priming and fertilization; PM0, Priming and no fertilization, and PMf, Priming and fertilization and LSD, Least Significant Difference.

an almost the same pattern. This means that the combina- 4.1.1 Days to emergence, seedling | tion of priming and micro‐dosing enormously increased both growth, and days to maturity grain and stover yields (Table 4). The increase in grain yield Across sites and experimental seasons (Tables 2 and 3), at Hawassa was more than double compared to Melkassa and primed plants emerged significantly earlier than no primed Ziway. Besides having relatively better soil fertility status, plants. Similarly, seedlings from primed plants had signifi- Hawassa receives higher amount of annual and seasonal rain- cantly higher percent seed germination, uniformity and vigor fall (Table 1). than the seedlings from no primed plants. Primed plants also matured significantly earlier than no primed plants. Primed but non fertilized plants tended to have the same pattern of 4.2 | Economic responses emergence rate, seedling uniformity, and vigor, as no prime Individually, both seed priming and fertilizer micro‐dos- but received fertilizer. Across sites and cropping seasons ing increased economic responses in maize (Table 5). (Tables 2 and 3), primed plants performed significantly Generally, like for agronomic performances, the highest (p ˂ .05) superior to no primed plants. returns were obtained at all sites when both priming and Fertilizer application did not significantly affect days to micro‐dosing were combined: fertilizer use efficiency, emergence and percent seed germination in neither primed value cost ratio, and gross margin were all improved across nor non primed seeds. However, it significantly increased sites (Table 5): seedling uniformity and vigor compared to no fertilized plants as well as to most no primed plants. No fertilizer, but primed plants tended to have similar seedling uniformity as 4.2.1 | Fertilizer use efficiency and value that of non primed but fertilized plants. However, they mostly cost ratio had significantly lower vigor. Fertilizer application to primed Across sites, fertilizer micro‐dosing increased both fertilizer plants further improved uniformity, vigor and days to ma- use efficiency and value cost ratio under both priming and turity (Tables 2 and 3), showing the synergy between seed no priming. This increase was much higher in Ziway and priming and fertilizer micro‐dosing. Melkasa. The increase in fertilizer use efficiency and value cost ratio was much higher under priming than no priming. Combining priming and micro‐dosing kept the value cost 4.1.2 Grain and stover yield | ratio above the minimum value of four (Table 5). The ferti- Across sites and cropping seasons, priming significantly lizer use efficiency also followed a similar pattern. increased maize stover and grain yields over no priming. Likewise, fertilizer application significantly increased stover and grain yields over non primed and non fertilized treat- 4.2.2 | Labor requirement, gross ment. Priming increased the average grain yield by 11, 8, and income, and gross margin 6% in Melkassa, Ziway, and Hawassa, respectively, com- Across sites (Table 6), the labor needed for priming was not pared to no priming. However, the grain yields were further significantly higher than no priming. However, it was sig- increased, respectively, by 75, 69, and 33%, when priming nificantly higher for fertilizer micro‐dosing compared to no was combined with micro‐dosing. Stover yields increased in fertilizer application even when combined with priming. 10 of 13 | SIME and AUNE There is no meaningful extra labor cost to be incurred for This combination in turn further reduce the vulnerability priming. Monetary returns to the use of priming were signifi- of maize to the impact of rainfall variability and terminal cantly increased over no priming. Monetary returns also in- drought in the central Rift Valley. These results are consistent creased by fertilizer application over no fertilizer. However, with other results that seed priming and fertilizer micro‐dos- the monetary returns were further increased when priming ing improves agronomic and economic returns of millet in and fertilizer micro‐dosing were combined. This showed low‐rainfall regions of Mali (Aune et al., 2012), of sorghum, that the economic returns were increased in an almost same sesame, groundnut, and cowpea in the semi‐arid Sudan way as agronomic returns for priming, micro‐dosing, or their (Abdalla et al., 2015), and of maize in semi‐arid Ethiopia combination. (Sime & Aune, 2016). Since seed priming reduces the risk of crop failure, it could therefore improve the interest of farmers to use fertilizers in maize production, with the combination 5 | DISCUSSION being a preferable option. The combination could, thus, pro- vide a win–win scenario for farmers. Studies in the central 5.1 | Maize establishment, duration to Rift Valley of Ethiopia showed that seasonal rainfall is highly maturity and yield unpredictable and variable with high risks of crop failure and In response to the prevailing rainfall variability and shorter low productivity (Belay et al., 2013), which escalates farm- window period for sowing and the cropping season in the ers’ risk‐averse behavior, discouraging them from investing central Rift Valley, this study used an early maturing maize in expensive fertilizers (Kassie et al., 2014). Previous stud- variety (var. Melkassa ‐ 2). The Melkassa Agricultural ies concluded that on‐farm seed priming is a simple, low Research Centre, Ethiopia, has released this variety. This cost, low risk intervention that represents a good insurance maize variety matures far earlier than local and hybrid maize for risk‐averse, resource‐poor farmers (Abdalla et al., 2015; varieties, which are also grown by the farmers. Priming has- Aune & Ousman, 2011; Camara et al., 2013; Hayashi et al., tens the earliness of this variety further. Thus, priming in- 2008; Osman et al., 2010). duced faster seed germination and shorter days to flowering On the other hand, the increase in average grain yield by and harvesting. The other priming‐related agronomic benefits 11, 8 and 6% in Melkassa, Ziway, and Hawassa, respectively, include higher seedling vigor, improved stand uniformity, showed that the benefits of seed priming over no priming better drought tolerance, and higher stover and grain yields. decrease with increasing rainfall. That is, priming is more These results are consistent with findings from previous stud- effective in areas receiving the relatively low amount of rain- ies (Harris, 2006; Harris et al., 1999, 2001; Harris, Rashid, fall. Melkassa and Ziway receive a lower amount of annual Hollington, Jasi, & Riches, 2002; Rashid et al., 2002). and seasonal rainfall than Hawassa. Likewise, the increase As priming shorten the duration of the maize crop, prim- in both fertilizer use efficiency and value cost ratio in Ziway ing can increase farmers’ choice of maize varieties to grow and Melkasa shows that fertilizer application is more effec- each season. Further, it can help farmers replant extra early tive in areas with relatively low soil fertility status. Melkassa maturing maize and haricot bean when a crop failure occurs and Ziway have poorer soil fertility condition than Hawassa, early in the season, providing farmers with additional crop- and hence the better response. This shows that coupling seed ping opportunities. Thus, priming can be taken as a good in- priming and fertilizer micro‐dosing is more effective and surance to the vulnerable farming system in the central Rift productive in relatively low‐rainfall and low soil fertility Valley. Belay, Recha, Woldeamanuel, and Morton (2017) re- condition. ported that 90% of farmers in the central Rift Valley have al- ready perceived climate variability, and 85% have attempted to adapt practices like crop diversification, planting date ad- 5.2 | Fertilizer profitability, gross justment, soil and water conservation and management, and margin, and agronomic fertilizer use efficiency increasing the intensity of inputs. Thus, further shortening of Priming does not increase labor over no priming, but increases the duration to maturity and harvest in maize by seed priming gross margin significantly. Priming reduces weed density and could be a viable, drought escaping strategy. increases pest tolerance. In agreement with a finding from a Fertilizer micro‐dosing at planting improves the agro- previous study (Harris, 2006), priming reduces the drudgery nomic performance of maize by improving seedling unifor- of weeding and pest management. Priming could offer these mity and vigor, shortening days to maturity and harvest, and indirect economic benefits. Micro‐dosing technique, on the higher yields. Fertilizer application does not improve emer- other hand, requires higher labor for fertilizer application. gence and percent seed germination. However, the benefit However, it offers higher fertilizer use efficiency, value cost of seed priming and micro‐dosing is considerably superior ratio, and gross margin. Following the variation in agro‐eco- when they are combined. The agronomic benefits resulting logical setting of the three study areas, the value cost ratio, from priming is further improved by fertilizer application. and the fertilizer use efficiency range between 7 and 10, and SIME and AUNE | 11 of 13 22 and 33, respectively. Fertilizer micro‐dosing increases percent seed germination were significantly improved both value cost ratio and fertilizer use efficiency, increases by fertilizer micro‐dosing. Combining seed priming and maize productivity and reduces the financial investment in micro‐dosing boosts the benefits that can be obtained from applying fertilizer, thereby minimizing the financial risk of either seed priming or micro‐dosing. The economic ben- farmers (Sime & Aune, 2014). This shows that micro‐dos- efits, including fertilizer use efficiency, value cost ratio ing can reduce farmers’ cash outlay and risk, thereby making and gross margin are improved in the same order. Shorter the use of fertilizer more attractive. In the Sahelian region, duration to maturity and harvest reduces vulnerability of it was indicated that crop productivity can be increased with maize to terminal drought and yield reduction. This could fertilizer micro‐dosing at a low cost and very moderate risk to encourage farmers to apply fertilizers. Farmers are reluc- farmers (Aune & Bationo, 2008). The combination of prim- tant to use the recommended fertilizer rate due to high ing with micro‐dosing also decreases the risk of investing in price and variable rainfall condition. The positive merits fertilizer, keeping the value cost ratio above the minimum of seed priming and micro‐dosing can give farmers a new requirement, which is consistent with findings from earlier option to increase yield. Combining seed priming and ferti- studies (Aune et al., 2012; Sime & Aune, 2016). Like for the lizer micro‐dosing offers the best agronomic performances agronomic returns, the combination increases the economic and economic returns in maize production. Contextually, benefits further compared to the economic benefits from these agricultural practices are new in the farming sys- either priming or micro‐dosing. Micro‐dosing of fertilizers tems in Ethiopia. They have a huge potential of increas- offers such a possibility to increase farm productivity, in ing agricultural productivity, particularly in the drylands. combination with priming yielding additional agronomic and This positive effect of on‐farm seed priming and fertilizer economic benefits (Sime & Aune, 2016), which substantiates micro‐dosing on maize agronomic performance and eco- the result from the present study. nomic return is particularly important in further increasing Regarding yield improvement due to treatment effects, the national attempt to increase the production of maize in authors’ previous studies and the present study, the treat- in Ethiopia. Finally, future research needs to test the com- ment that actually work better is the combined use of seed bined benefits of seed priming and fertilizer micro‐dosing priming and fertilizer micro‐dosing. Irrespective of tillage with other crops and under different rainfall conditions. systems (conventional and conservation tillage systems), The author recommends dissemination of the technologies this treatment performs better in terms of agronomic perfor- to a wide range of farmers to improve the agronomic and mances and economic returns in maize. The performance of economic performances of maize. We are planning to work this treatment is consistent with both authors’ previous stud- with, farmers, agricultural researchers, and policymakers ies and the present study. In the author's opinion, the results on the dissemination of the technologies to improve the from this study, thus, add additional information to what is agronomic and economic performances of maize under dif- already known about these technologies. Particularly, the ferent agro‐ecological conditions. promising agronomic and economic responses from combin- ing priming and micro‐dosing added novelty of the present ACKNOWLEDGMENTS study. Furthermore, studies on the economic responses from combined seed priming and micro‐dosing are scanty, partic- The Norwegian Ministry of Foreign Affairs funded this ularly in SSA. Thus, the results from these studies suggest research through the institutional collaboration between that these technologies to be a viable option in the SSA agri- Hawassa University, Ethiopia and Norwegian University of cultural system. Particularly, farmers who operate in the dry Life Sciences, NMBU, Norway. The agricultural extension lands, with variable rainfall and severe soil moisture stress workers, experts, and farmers are grateful for their unre- and soil fertility, can be potential beneficiaries of priming or served assistance during the experimentation time. They pro- its combination with micro‐dosing. vided useful insights and assistance to the researchers. The district agriculture and rural offices are also thanked for their generous hospitality and support. 6 | CONCLUSION CONFLICT OF INTERESTS On‐farm seed priming and fertilizer micro‐dosing are a cheap, low risk, productive, and profitable techniques in The author declares that there are no competing interests. maize production. Days to emergence, percent seed ger- mination, seedling uniformity and vigor, days to maturity, ORCID stover, and grain yields were all significantly improved by priming seed with water. All the yield components except Getachew Sime https://orcid.org/0000-0002-4406-3770 12 of 13 | SIME and AUNE REFERENCES Finch‐Savage, W. E., Dent, K. C., & Clark, L. J. (2004). Soak conditions and temperature following sowing influence the response of maize (Zea Abdalla, E. A., Osman, A. K., Maki, M. A., Nur, F. M., Ali, S. 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